How to run some functions in an addon in blender start?
In user preferences choose add-ons tab check the box of the plugin you want to use and hit save user settings in lower left corner.
If the plugin is not enabled next time you open blender then either you are doing something wrong (like, the shortcut of the plugin activation is diffrent than you think or plugin is updated and changed it's interface so it doesn't appears in the same spot as shown in tutorials) or the plugin is glitched.

Try repeating these steps and downloading and using latest version of the plugin.